In the semiconductor industry, an ever-increasing desire exists to manufacture smaller structures with high accuracy and reliability. Lithography is often a critical part of such manufacturing processes. During lithography processing, the target (e.g. a semiconductor wafer) needs to be situated in a high vacuum environment that is hermetically sealed from the surroundings (e.g. from atmospheric conditions), to reduce the probability of contamination.
In a mask-less lithography system, charged particle beamlets may be used to transfer a pattern onto the target. The beamlets may be individually controllable to obtain the desired pattern. To be commercially viable, mask-less lithography systems need to meet challenging demands for wafer throughput and error margins. A higher throughput may be obtained by using more beamlets. The handling of a greater number of beamlets calls for more sophisticated control devices and circuitry, without compromising the necessary vacuum conditions or significantly increasing the required fab space (i.e. the area covered by the processing unit). The task of arranging more process control devices and/or circuitry in a decreasing available volume while maintaining hermetic seals between various parts of the lithography system becomes more and more challenging.
Patent document U.S. Pat. No. 8,242,467B2, assigned to the current applicant, discloses a multi-beamlet lithography system. This system comprises a beamlet blanker (or modulator) for selectively allowing or denying individual beamlets passage to the target, based on pattern data. The beamlet blanker is arranged near the target in a vacuum chamber, but controlled by a control unit that is located outside the vacuum chamber. The lithography system includes an optic system with an array of optical fibers for transmitting modulated light signals with the pattern data from the control unit to light sensitive blanking actuators on the beamlet blanker. The fibers are routed via an opening in a feedthrough device through a wall of the vacuum chamber. Vacuum compatible sealing material is used to provide an airtight sealing for the fibers in the opening. U.S. Pat. No. 8,242,467B2 presents little details in relation to the structure of the feedthrough device.
Patent document US2016/0787599A1 describes fiber alignment assemblies for hermetically feeding optical fibers through a housing of an opto-electronic module. One such assembly includes a ferrule, with two adjoined ferrule portions. One ferrule portion has a surface with four alignment grooves, which accommodate end sections of optical fibers. The second ferrule portion covers the surface and the alignment grooves of the first ferrule portion, when the ferrule portions are mated together to form the ferrule. Sealant material, such as glass solder, may then be fed into the ferrule, through an aperture in one of the ferrule portions. Vacuum is applied to a pocket in the ferrule, to draw the glass solder through clearances between the optical fibers and grooves, to form a hermetic seal. The hermetic assemblies from US2016/0787599A1 are primarily suitable for feeding through relatively small numbers of individual optical fibers.
It would be desirable to provide a feedthrough device that is suitable for routing a large number of optical fibers (i.e. several tens or hundreds) in an ordered and hermetically sealed manner through a structure that separates two regions with different ambient conditions.